I would say privacy. No telemetry, no targeted ads, no centralized transcripts, possibly end to end encryption. Psychiatrists are bound by professional secrecy, and they touch on very sensitive topics (people’s fears, their private lives, sexual preferences, …). Privacy is a very strong concern if you want to build this kind of platform.
I can work on privacy segment well enough that both parties agrees on onboarding like only no recording is allowed in any way, no screenshots or online notes form the doctor's side.